Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions

Investigation of occurrence of aromatic amines in municipal wastewaters using passive sampling

Aromatic amines (AAs) are human-made compounds known for their mutagenic properties, entering surface waters from various sources, often originating as transformation products of dyes or pesticides. Despite their low concentrations in surface waters, AAs can exhibit mutagenicity. Our study focused on evaluating three passive samplers (PSs) for enriching these compounds from influent and effluent of a wastewater treatment plant (WWTP) in Brno, Czech Republic. The PSs tested included variants containing AttractSPE™ SDB-RPS sorbent disk, one with and one without a diffusive agarose hydrogel layer, and a modified Speedisk (Bakerbond Speedisk® H2O-Philic). PSs were deployed in wastewater (WW) for one to four weeks in various overlapping combinations, and the uptake of AAs to PSs was compared to their concentrations in 24-hour composite water samples. A targeted LC/MS analysis covered 42 amines, detecting 11 and 13 AAs in daily composite influent and effluent samples, respectively. In the influent, AAs ranged from 1.5 ng L-1 for 1-anilinonaphthalene to 1.0 μg L-1 for aniline, and the highest concentration among all measured amines was observed for cyclohexylamine at 2.9 μg L-1. In the effluent, concentrations ranged from 0.5 ng L-1 for 1-anilinonaphthalene to 88 ng L-1 for o-anisidine. PSs demonstrated comparable accumulation of amines, with integrative uptake up to 28 days in both influent and effluent and detection of up to 23 and 27 amines in influent and effluent, respectively; altogether 34 compounds were detected in the study. Sampling rates (Rs) were estimated for compounds present in at least 50 % of the samples and showing <40 % aqueous concentration variability, with robustness evaluated by comparing values for compounds in WWTP influent and effluent. Although all devices performed similarly, hydrogel-based PS exhibited superior performance in several criteria, including time integration and robustness of sampling rates, making it a suitable monitoring tool for AAs in WW.

Evaluation of the DGT passive samplers for integrating fluctuating concentrations of pharmaceuticals in surface water

Diffusive gradients in thin films (DGTs) have been well-documented for the measurement of a broad range of organic pollutants in surface water. However, the performance has been challenged by the inherent periodic concentration fluctuations for most organic pollutants. Therefore, there is an urgent need to assess the true time-weighted average (TWA) concentration based on fluctuating concentration profiles. The study aimed to evaluate the responsiveness of DGT and accuracy of TWA concentrations, considering various concentration fluctuating scenarios of 20 pharmaceuticals in surface water. The reliability and accuracy of the TWA concentrations measured by the DGT were assessed by comparison with the sum of cumulative mass of DGT exposed at different stages over the deployment period. The results showed that peak concentration duration (1-5 days), peak concentration fluctuation intensity (6-20 times), and occurrence time of peak concentration fluctuation (early, middle, and late stages) have minimal effect on DGT's response to most target pharmaceutical concentration fluctuations (0.8 < CDGT/CTWA < 1.2). While the downward-bent accumulations of a few pharmaceuticals on DGT occur as the sampling time increases, which could be accounted for by capacity effects during a long-time sampling period. Additionally, the DGT device had good sampling performance in recording short fluctuating concentrations from a pulse event returning to background concentrations with variable intensity and duration. This study revealed a satisfactory capacity for the evaluation of the TWA concentration of pharmaceuticals integrated over the period of different pulse deployment for DGT, suggesting that this passive sampler is ideally suited as a monitoring tool for field application. This study represents the first trial for evaluating DGT sampling performance for pharmaceuticals with multiple concentration fluctuating scenarios over time, which would be valuable for assessing the pollution status in future monitoring campaign.

Prediction of the accumulation behavior of pesticides in PDMS-coated stir bars used as passive samplers in freshwaters

Passive samplers accumulate organic contaminants at rates that depend on in-field exposure conditions such as freshwater flow velocity, water temperature and water quality. Time-weighted average concentrations can be determined by using a correction process such as the performance reference compound (PRC) method. This study presented a new approach to predict the accumulation behavior of pesticides in polydimethylsiloxane-coated stir bars under different exposure conditions and assign a specific PRC to each pesticide for quantitative purposes. We used an experimental design with eight simultaneous accumulation kinetics of 13 pesticides and elimination kinetics of three PRC candidates run in a flow-through system to determine the effects of flow velocity, water temperature and dissolved organic matter on the kinetic constants. We identified the parameters that had a significant effect on the accumulation of each pesticide and assigned a PRC candidate to each pesticide. We then used a discriminant function analysis to find the parameters that had a significant effect on accumulation of the 13 pesticides via their physical-chemical properties and to predict through a stochastic approach the parameters for seven other pesticides. This approach provides a better framework for identifying a PRC than conventional methods to determine unbiased concentrations in future monitoring efforts.

Factors affecting diffusion of polar organic compounds in agarose hydrogel applied to control mass transfer in passive samplers

Diffusive hydrogel-based passive sampler (HPS) based on diffusive gradients in thin films (DGT) is designed for monitoring polar organic contaminants in the aquatic environment. DGT technique controls the compound's overall uptake rate by adding a hydrogel layer of known thickness, which minimizes the importance of the resistive water boundary layer in the compound uptake process. In this work, we investigated several factors which may influence the diffusion of a range of aquatic contaminants in 1.5% agarose hydrogel. Diffusion in hydrogel was tested using the sheet stacking method. We demonstrated that a thin nylon netting incorporated into the diffusive hydrogel for mechanical strengthening does not significantly affect the diffusion of 11 perfluoroalkyl compounds. Further, we investigated the effect of pH in the range from 3 to 11 on the diffusion of a range of 39 aromatic amines (AAs) -36 aromatic, 2 aliphatic, and azobenzene in hydrogel. AAs were chosen as representatives of compounds with pH-dependent dissociation in water. Analysis of variance showed no significant difference in mean diffusion coefficient log D value at five pH values. The demonstration that the diffusion coefficient D and thus the sampling rate Rs are independent on pH simplifies the interpretation of data from field studies because we can neglect the influence of pH on the Rs. log D values (m2 s-1) of tested AAs ranged from to - 9.77 for 3,3'-dimethylbenzidine to - 9.19 for azobenzene. A negative correlation of log D with molar mass (log M) and molecular volume (log Vm) was observed (R =  - 0.57 and - 0.56, respectively). The diffusion coefficient presents a critical parameter for the sampling rate estimation of HPS. Theoretical sampling rates Rs of AAs were calculated for a HPS using the average D values. Theoretical Rs values calculated for AAs at 22°C ranged from 29 mL day-1 for 3,3'-dimethylbenzidine to 106 mL day-1 for 2-aminopyridine. Our calculated values of Rs are in the same range as those already published for a range of low-molecular polar organic contaminants, which supports the possibility of deriving sampler performance parameters in the field from laboratory-derived diffusivity of analytes in hydrogel.

Performance evaluation of a diffusive hydrogel-based passive sampler for monitoring of polar organic compounds in wastewater

An upscaled passive sampler variant (diffusive hydrogel-based passive sampler; HPS) based on diffusive gradients in thin films for polar organic compounds (o-DGT) with seven times higher surface area (22.7 cm²) than a typical o-DGT sampler (3.14 cm²) was tested in several field studies. HPS performance was tested in situ within a calibration study in the treated effluent of a municipal wastewater treatment plant and in a verification study in the raw municipal wastewater influent. HPS sampled integratively for up to 14 days in the effluent, and 8 days in the influent. Sampling rates (R_s) were derived for 44 pharmaceuticals and personal care products, 3 perfluoroalkyl substances, 2 anticorrosives, and 21 pesticides and metabolites, ranging from 6 to 132 mL d^-1. Robustness and repeatability of HPS deteriorated after exposures longer than 14 days due to microbial and physical damage of the diffusive agarose layer. In situ R_s values for the HPS can be applied to estimate the aqueous concentration of the calibrated polar organic compounds in wastewater within an uncertainty factor of four. When accepting this level of accuracy, the HPS can be applied for monitoring trends of organic micropollutants in wastewater.

Occurrences, distribution and risk assessment of polar pesticides in Niger River valley and its tributary the Mekrou River (Niger Republic)

The increase in food needs due to high population growth in Niger has led to the intensification of urban agriculture and the increased use of pesticides. The objective of this study is primarily to assess the polar pesticide contamination (mainly herbicides) of the Niger River and its tributary, the Mekrou River, in Niger, using both grab sampling and POCIS (Polar Organic Chemical Integrative Samplers), and then to evaluate the risk to the aquatic environment. Two water sampling campaigns were carried out during the wet and dry seasons. The polar pesticides were analyzed by liquid chromatography coupled with tandem mass spectrometry, which allowed the identification of compounds with concentrations in the grab samples above the WHO guide values and the EU directive: diuron with 2221 ng/L (EU quality guideline: 200 ng/L), atrazine with 742 ng/L (EU quality guideline: 600 ng/L) and acetochlor with 238 ng/L (EU quality guideline: 100 ng/L). The risk assessment study indicated that diuron and atrazine present a high risk for the aquatic environment during the wet season. The main source of water contamination is the intensive use of pesticides in urban agriculture near the city of Niamey, and the intensive cotton farming in the Benin. Moreover, the surveys (30 producers interviewed) showed that 70% of the pesticides used are not approved by the Interstate Committee for Drought Control in the Sahel (CILSS) and some are prohibited in Niger. The inventory of pesticides sold in the zone showed that active ingredients used by producers are 48% insecticides, 45% herbicides, and 7% fungicides.

A Review of In Situ Methods-Solid Phase Adsorption Toxin Tracking (SPATT) and Polar Organic Chemical Integrative Sampler (POCIS) for the Collection and Concentration of Marine Biotoxins and Pharmaceuticals in Environmental Waters

Solid Phase Adsorption Toxin Tracking (SPATT) and Polar Organic Chemical Integrative Sampler (POCIS) are in situ methods that have been applied to pre-concentrate a range of marine toxins, pesticides and pharmaceutical compounds that occur at low levels in marine and environmental waters. Recent research has identified the widespread distribution of biotoxins and pharmaceuticals in environmental waters (marine, brackish and freshwater) highlighting the need for the development of effective techniques to generate accurate quantitative water system profiles. In this manuscript, we reviewed in situ methods known as Solid Phase Adsorption Toxin Tracking (SPATT) and Polar Organic Chemical Integrative Sampler (POCIS) for the collection and concentration of marine biotoxins, freshwater cyanotoxins and pharmaceuticals in environmental waters since the 1980s to present. Twelve different adsorption substrates in SPATT and 18 different sorbents in POCIS were reviewed for their ability to absorb a range of lipophilic and hydrophilic marine biotoxins, pharmaceuticals, pesticides, antibiotics and microcystins in marine water, freshwater and wastewater. This review suggests the gaps in reported studies, outlines future research possibilities and guides researchers who wish to work on water contaminates using Solid Phase Adsorption Toxin Tracking (SPATT) and Polar Organic Chemical Integrative Sampler (POCIS) technologies.

Do pesticides degrade in surface water receiving runoff from agricultural catchments? Combining passive samplers (POCIS) and compound-specific isotope analysis

Pesticides lead to surface water pollution and ecotoxicological effects on aquatic biota. Novel strategies are required to evaluate the contribution of degradation to the overall pesticide dissipation in surface waters. Here, we combined polar organic chemical integrative samplers (POCIS) with compound-specific isotope analysis (CSIA) to trace in situ pesticide degradation in artificial ponds and agricultural streams. The application of pesticide CSIA to surface waters is currently restricted due to environmental concentrations in the low μg.L^-1 range, requiring processing of large water volumes. A series of laboratory experiments showed that POCIS enables preconcentration and accurate recording of the carbon isotope signatures (δ¹³C) of common pesticides under simulated surface water conditions and for various scenarios. Commercial and in-house POCIS did not significantly (Δδ¹³C < 1 %) change the δ¹³C of pesticides during uptake, extraction, and δ¹³C measurements of pesticides, independently of the pesticide concentrations (1-10 μg.L^-1) or the flow speeds (6 or 14 cm.s^-1). However, simulated rainfall events of pesticide runoff affected the δ¹³C of pesticides in POCIS. In-house POCIS coupled with CSIA of pesticides were also tested under different field conditions, including three flow-through and off-stream ponds and one stream receiving pesticides from agricultural catchments. The POCIS-CSIA method enabled to determine whether degradation of S-metolachlor and dimethomorph mainly occurred in agricultural soil or surface waters. Comparison of δ¹³C of S-metolachlor in POCIS deployed in a stream with δ¹³C of S-metolachlor in commercial formulations suggested runoff of fresh S-metolachlor in the midstream sampling site, which was not recorded in grab samples. Altogether, our study highlights that the POCIS-CSIA approach represents a unique opportunity to evaluate the contribution of degradation to the overall dissipation of pesticides in surface waters.

Carbon nanotube-passive samplers as novel tools for sampling and determining micropollutants in the aquatic environment

Passive sampling is an interesting and cost-effective strategy for the quantification of micropollutants in the aquatic environment. When combined especially with a sensitive analytical method such as liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS), the use of passive sampling devices (PSDs) enables long-term and reliable determination of a wide range of chemicals. In this study, carbon nanotubes (CNTs) were used as an innovative sorbent in POCIS-like samplers (Polar Organic Chemical Integrative Sampler). The developed CNTs-PSDs were calibrated by the flow-through method and the obtained sampling rates (R_s) of analytes were compared with the previously obtained R_s values using the semi-static method. Subsequently, passive samplers were placed in the Baltic Sea, the Nogat River, and the Sztumskie Pole Lake in order to sample and concentrate 28 chemical compounds belonging to the group of contaminants of emerging concern (CECs). For the first time, the effectiveness of the use of CNTs-PSDs in the field was proven by the quantification of carbamazepine, diclofenac, p-nitrophenol, bisphenol A, 3,5-dichlorophenol, 17-β-estradiol, 17-α-ethinylestradiol and metoprolol in the tested surface waters. The obtained time-weighted average (TWA) concentrations of analytes ranged from 0.22 ± 0.12 ng/L (for metoprolol in the Nogat River) to 32.1 ± 2.4 ng/L (for bisphenol A in the Sztumskie Pole Lake). More importantly, CNTs-PSDs determined a greater amount of micropollutants than grab sampling and solid-phase extraction (SPE), which proves the advantage of passive sampling over grab sampling, especially when monitoring contaminants in the aquatic environment at low concentration levels.

Impact of environmental factors on the sampling rate of β-blockers and sulfonamides from water by a carbon nanotube-passive sampler

Passive techniques are a constantly evolving approach to the long-term monitoring of micropollutants, including pharmaceuticals, in the aquatic environment. This paper presents, for the first time, the calibration results of a new CNTs-PSDs (carbon nanotubes used as a sorbent in passive sampling devices) with an examination of the effect of donor phase salinity, water pH and the concentration of dissolved humic acids (DHAs), using both ultrapure and environmental waters. Sampling rates (R_s) were determined for the developed kinetic samplers. It has been observed that the impact of the examined environmental factors on the R_s values strictly depends on the type of the analytes. In the case of β-blockers, the only environmental parameter affecting their uptake rate was the salinity of water. A certain relationship was noted, namely the higher the salt concentration in water, the lower the R_s values of β-blockers. In the case of sulfonamides, water salinity, water pH 7-9 and DHAs concentration decreased the uptake rate of these compounds by CNTs-PSDs. The determined R_s values differed in particular when the values obtained from the experiments carried out using ultrapure water and environmental waters were compared. The general conclusion is that the calibration of novel CNTs-PSDs should be carried out under physicochemical conditions of the aquatic phase that are similar to the environmental matrix.

Sampling Rate of Polar Organic Chemical Integrative Sampler (POCIS): Influence Factors and Calibration Methods

As a passive sampling device, the polar organic chemical integrative sampler (POCIS) has the characteristics of simple operation, safety, and reliability for assessing the occurrence and risk of persistent and emerging trace organic pollutants. The POCIS, allowing for the determination of time-weighted average (TWA) concentration of polar organic chemicals, exhibits good application prospects in aquatic environments. Before deploying the device in water, the sampling rate (Rs), which is a key parameter for characterizing pollutant enrichment, should be determined and calibrated accurately. However, the Rs values strongly depend on experimental hydrodynamic conditions. This paper provides an overview of the current situation of the POCIS for environmental monitoring of organic pollutants in an aquatic system. The principle and theory of the POCIS are outlined. In particular, the effect factors such as the ambient conditions, pollutant properties, and device features on the Rs are analyzed in detail from aspects of impact dependence and mechanisms. The calibration methods of the Rs under laboratory and in situ conditions are summarized. This review offers supplementary information on comprehensive understanding of mechanism and application of the POCIS. Nevertheless, the Rs were impacted by a combined effect of solute–sorbent–membrane–solution, and the influence extent of each variable was still unclear. On this basis, the ongoing challenges are proposed for the future application of the POCIS in the actual environment, for instance, the need for this device to be improved in terms of quantitative methods for more accurate measurement of the Rs.

Experimental Estimation of 44 Pharmaceutical Polar Organic Chemical Integrative Sampler Sampling Rates in an Artificial River under Various Flow Conditions

The present study pertains to a polar organic chemical integrative sampler (POCIS) laboratory calibration to estimate the sampling rates for 44 pharmaceuticals featuring a wide range of polarity (-0.6 < octanol/water partition coefficient [log K_OW ] < 5.4). The calibration was performed at 16.0 ± 1.5 °C for 4 water flow velocities (0, 2-3, 6-7, and 20 cm/s) in both a tank (for calibration at 0 cm/s) and a laboratory-scale artificial river filled with 200 and 500 L of tap water spiked with 0.3 µg/L of each compound, respectively. Twelve new sampling rates and 26 sampling rates already available in the literature were determined, whereas the sampling rates for 6 pharmaceuticals could not be determined due to nonlinearity or poor accumulation in POCIS. An increase in the sampling rate value with flow velocity was observed, which is consistent with a decrease in the effective thickness of the water boundary layer at the POCIS membrane surface. Environ Toxicol Chem 2020;39:1186-1195. © 2020 SETAC.

Estimating 42 pesticide sampling rates by POCIS and POCIS-MIP samplers for groundwater monitoring: a pilot-scale calibration

Pesticides occur in groundwater as a result of agricultural activity. Their monitoring under the Water Framework Directive is based on only a few spot-sampling measurements per year despite their temporal variability. Passive sampling, which was successfully tested in surface water to provide a more representative assessment of contamination, could be applied to groundwater for a better definition of its contamination. However, few reliable calibration data under low water flow are available. The objective of our study thus consisted in determining sampling rates by two types of passive samplers, a POCIS (polar organic chemical integrative sampler) for polar pesticides, and a POCIS-MIP sampler based on a receiving phase of molecular imprinted polymers, specific for AMPA and glyphosate under low flow conditions as exist in groundwater. To our knowledge, this is the first time that sampling rates (sampling rate represents the volume of water from which the analyte is quantitatively extracted by the sampler per unit time) are estimated for groundwater applications. Our calibrations took place in an experimental pilot filled with groundwater and with low water flow (a few metres per day). Pesticide uptake in POCIS showed good linearity, with up to 28 days before reaching equilibrium. Two types of accumulation in POCIS were noted (a linear pattern up to 28 days, and after a time lag of 7 to 14 days). Sampling rates for 38 compounds were calculated and compared with those available in the literature or obtained previously under laboratory conditions. The values obtained were lower by a factor 1 to 14 than those estimated under stirring conditions in the literature, whereas water flow velocity (m s^-1) differed by a factor of 2000 to 10,000.

An improved design of a passive sampler for polar organic compounds based on diffusion in agarose hydrogel

Passive samplers based on diffusive gradients in thin hydrogel films (DGT) were recently modified for sampling of polar organic compounds in water. However, since the sampling rates of the commonly used DGT design with the surface area of 3.1 cm² are low, we propose to increase them by applying a two-sided design with a larger sampling surface area of 22.7 cm². The sampler design consists of two sorptive hydrogel disks compressed between two diffusive hydrogel disk layers strengthened by nylon netting and held together by two stainless steel rings. Sorbent/water distribution coefficients (K_SW) were determined, and the sampler was calibrated for monitoring 11 perfluoroalkyl substances and 12 pharmaceuticals and personal care products in water at laboratory conditions using a closed system with artificial flow generated by submersible pumps. A field performance test was conducted at five locations in the Morava River basin in Czech Republic. The median value of laboratory-derived sampling rates was 43 mL day^-1 with extreme values of 2 mL day^-1 and 90 mL day^-1 for perfluorotridecanoic and perfluoroheptanoic acids, respectively. The log K_SW values of tested compounds ranged from 3.18 to 5.47 L kg^-1, and the estimated halftime to attain sampler-water equilibrium ranged from 2 days to more than 28 days, which is the maximum recommended exposure period, considering potential issues with the stability of hydrogel. The sampler can be used for assessment of spatial trends as well as estimation of aqueous concentration of investigated polar compounds.

Evaluating polar pesticide pollution with a combined approach: a survey of agricultural practices and POCIS passive samplers in a Tunisian lagoon watershed

A study of pesticides in the Bizerte lagoon watershed on the Mediterranean coast of Tunisia showed that herbicides and fungicides are the most commonly used compounds. A survey was made of selected farmers. Pesticide contamination was monitored in the water column and sediments at four selected sampling sites (lagoon (A) and in three oueds-Chegui (B), Garaa (C), and Tinja (D)). Polar organic chemical integrative samplers (POCIS) were used to assess pesticide contamination. Thirty-two pesticides were investigated; the total concentration of active ingredients ranged from 35.9 ng L^-1 in Tinja oued to 1246 ng L^-1 in Chegui oued. In the lagoon, the total concentration of pesticides was 67.7 ng L^-1. In the sediments, the highest concentration was measured in Chegui oued in the spring (31 ng g^-1 dw). The main compounds found in the analyzed sediments were prosulfocarb and tebuconazole molecules.

Effects of hydrodynamic conditions and temperature on polar organic chemical integrative sampling rates

The effects of changing hydrodynamic conditions and changing temperatures on polar organic chemical integrative sampler (POCIS) sampling rates (R_s ) were investigated for 12 crop protection chemicals. Exposure concentration was held constant in each laboratory experiment, and flow velocities were calculated from measured mass transfer coefficients of the water boundary layer near the surface of POCIS devices. At a given temperature R_s generally increased by a factor of 2 to 5 between a stagnant condition and higher flow velocities (6-21 cm/s), but R_s for most compounds was essentially constant between the higher flow velocities. When temperature was varied between 8 and 39 °C for a given flow condition, R_s increased linearly. In general, R_s increased by a factor of 2 to 4 and 2 to 8 over this temperature range under flow and stagnant conditions, respectively. An Arrhenius model was used to describe the dependence of POCIS sampling rates on temperature. Adjustments of R_s for temperature did not fully explain observed differences between time-weighted average concentrations of atrazine determined from POCIS and from composite water sampling in a field setting, suggesting that the effects of other competing factors still need to be evaluated. Environ Toxicol Chem 2018;37:2331-2339. © 2018 SETAC.

Comparison of the sampling rates and partitioning behaviour of polar and non-polar contaminants in the polar organic chemical integrative sampler and a monophasic mixed polymer sampler for application as an equilibrium passive sampler

In this work, Oasis HLB® beads were embedded in a silicone matrix to make a single phase passive sampler with a higher affinity for polar and ionisable compounds than silicone alone. The applicability of this mixed polymer sampler (MPS) was investigated for 34 aquatic contaminants (log K_OW -0.03 to 6.26) in batch experiments. The influence of flow was investigated by comparing uptake under static and stirred conditions. The sampler characteristics of the MPS was assessed in terms of sampling rates (R_S) and sampler-water partition coefficients (K_SW), and these were compared to those of the polar organic chemical integrative sampler (POCIS) as a reference kinetic passive sampler. The MPS was characterized as an equilibrium sampler for both polar and non-polar compounds, with faster uptake rates and a shorter time to reach equilibrium than the POCIS. Water flow rate impacted sampling rates by up to a factor of 12 when comparing static and stirred conditions. In addition, the relative accumulation of compounds in the polyethersulfone (PES) membranes versus the inner Oasis HLB sorbent was compared for the POCIS, and ranged from <1% to 83% depending on the analyte properties. This is indicative of a potentially significant lag-phase for less polar compounds within POCIS. The findings of this study can be used to quantitatively describe the partitioning and kinetic behaviour of MPS and POCIS for a range of aquatic organic contaminants for application in field sampling.

Polar pesticide contamination of an urban and peri-urban tropical watershed affected by agricultural activities (Yaoundé, Center Region, Cameroon)

Urban agriculture is crucial to local populations, but the risk of it contaminating water has rarely been documented. The aim of this study was to assess pesticide contamination of surface waters from the Méfou watershed (Yaoundé, Cameroon) by 32 selected herbicides, fungicides, and insecticides (mainly polar) according to their local application, using both grab sampling and polar organic compounds integrative samplers (POCIS). Three sampling campaigns were conducted in the March/April and October/November 2015 and June/July 2016 rainy seasons in urban and peri-urban areas. The majority of the targeted compounds were detected. The quantification frequencies of eight pesticides were more than 20% with both POCIS and grab sampling, and that of diuron and atrazine reached 100%. Spatial differences in contamination were evidenced with higher contamination in urban than peri-urban rivers. In particular, diuron was identified as an urban contaminant of concern because its concentrations frequently exceeded the European water quality guideline of 0.200 μg/L in freshwater and may thus represent an ecological risk due to a risk quotient > 1 for algae observed in 94% of grab samples. This study raises concerns about the impacts of urban agriculture on the quality of water resources and to a larger extent on the health of the inhabitants of cities in developing countries. Graphical abstract ᅟ.

Grab and passive sampling applied to pesticide analysis in the São Lourenço river headwater in Campo Verde - MT, Brazil

In this study, the quality of surface water in the headwaters of São Lourenço River in Mato Grosso, Brazil, was evaluated in relation to contamination by pesticides. For this purpose, samples were collected between December 2015 and June 2016 by grab sampling and by passive sampling using an integrative polar organic compound sampler installed in the field during four 14-day cycles between March and June 2016. The analyses were performed by gas chromatography (CG/MS) and by liquid chromatography (UPLC-MS/MS). The results showed the detection of two pesticides (atrazine and pyraclostrobin) of the five analyzed by passive sampling and eight active principles among the 20 analyzed (malathion, diuron, carbofuran, carbendazim, trifluralin, imidacloprid, metolachlor, and acetamiprid) by grab sampling. The detection of 10 pesticides, even almost a decade after the beginning of a recovery process of the ciliary forest, confirms the headwaters' vulnerability to these contaminants and passive sampling proved to be an important tool in capturing small concentrations of pesticides constituting an interesting complement to grab sampling.

Determining the suitability of a polar organic chemical integrated sampler (POCIS) for the detection of pesticide residue in the Ishikawa River and its tributary in Osaka, Japan

The monitoring of pesticide concentrations in Japanese rivers was conducted via a grab sampling method and a passive sampling method using the polar organic chemical integrated sampler (POCIS). The results showed that cumulative detections were 84 with grab sampling and 98 with the POCIS. All of the pesticides detected by grab sampling could be quantified with a POCIS except for one (although its traces were detected). In addition, 15 detections quantified by POCIS were undetected by grab sampling. The average concentrations of pesticides detected by both the POCIS and grab sampling during the investigation period were compared. A good correlation was observed between the two methods with a slope of 1.00 and a coefficient of correlation (r) of 0.897 (n=79). Although high temporal variability was observed in the pesticide concentrations by grab sampling, the average pesticide concentrations obtained by the two methods showed similar values during the investigation period.

Investigation of polar organic chemical integrative sampler (POCIS) flow rate dependence for munition constituents in underwater environments

Munition constituents (MC) are present in aquatic environments throughout the world. Potential for fluctuating release with low residence times may cause concentrations of MC to vary widely over time at contaminated sites. Recently, polar organic chemical integrative samplers (POCIS) have been demonstrated to be valuable tools for the environmental exposure assessment of MC in water. Flow rate is known to influence sampling by POCIS. Because POCIS sampling rates (R_s) for MC have only been determined under quasi-static conditions, the present study evaluated the uptake of 2,4,6-trinitrotoluene (TNT), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and 2,4- and 2,6-dinitrotoluenes (DNT), by POCIS in a controlled water flume at 7, 15, and 30 cm/s in 10-day experiments using samplers both within and without a protective cage. Sampling rate increased with flow rate for all MC investigated, but flow rate had the strongest impact on TNT and the weakest impact on RDX. For uncaged POCIS, mean R_s for 30 cm/s was significantly higher than that for 7 cm by 2.7, 1.9, 1.9, and 1.3 folds for TNT, 2,4-DNT, 2,6-DNT, and RDX, respectively. For all MC except RDX, mean R_s for caged POCIS at 7 cm/s were significantly lower than for uncaged samplers and similar to those measured at quasi-static condition, but except for 2,6-DNT, no caging effect was measured at the highest flow rate, indicating that the impact of caging on R_s is flow rate-dependent. When flow rates are known, flow rate-specific R_s should be used for generating POCIS-derived time-averaged concentrations of MC at contaminated sites.

DGT Passive Sampling for Quantitative in Situ Measurements of Compounds from Household and Personal Care Products in Waters

Widespread use of organic chemicals in household and personal care products (HPCPs) and their discharge into aquatic systems means reliable, robust techniques to monitor environmental concentrations are needed. The passive sampling approach of diffusive gradients in thin-films (DGT) is developed here and demonstrated to provide in situ quantitative and time-weighted average (TWA) measurement of these chemicals in waters. The novel technique is developed for HPCPs, including preservatives, antioxidants and disinfectants, by evaluating the performance of different binding agents. Ultrasonic extraction of binding gels in acetonitrile gave good and consistent recoveries for all test chemicals. Uptake by DGT with HLB (hydrophilic-lipophilic-balanced) as the binding agent was relatively independent of pH (3.5-9.5), ionic strength (0.001-0.1 M) and dissolved organic matter (0-20 mg L^-1), making it suitable for applications across a wide range of environments. Deployment time and diffusion layer thickness dependence experiments confirmed DGT accumulated chemicals masses are consistent with theoretical predictions. The technique was further tested and applied in the influent and effluent of a wastewater treatment plant. Results were compared with conventional grab-sampling and 24-h-composited samples from autosamplers. DGT provided TWA concentrations over up to 18 days deployment, with minimal effects from biofouling or the diffusive boundary layer. The field application demonstrated advantages of the DGT technique: it gives in situ analyte preconcentration in a simple matrix, with more quantitative measurement of the HPCP analytes.

Monitoring Herbicide Concentrations and Loads during a Flood Event: A Comparison of Grab Sampling with Passive Sampling

The suitability of passive samplers (Chemcatcher) as an alternative to grab sampling in estimating time-weighted average (TWA) concentrations and total loads of herbicides was assessed. Grab sampling complemented deployments of passive samplers in a tropical waterway in Queensland, Australia, before, during and after a flood event. Good agreement was observed between the two sampling modes in estimating TWA concentrations that was independent of herbicide concentrations ranging over 2 orders of magnitude. In a flood-specific deployment, passive sampler TWA concentrations underestimated mean grab sampler (n = 258) derived concentrations of atrazine, diuron, ametryn, and metolachlor by an average factor of 1.29. No clear trends were evident in the ratios of load estimates from passive samplers relative to grab samples that ranged between 0.3 and 1.8 for these analytes because of the limitations of using TWA concentrations to derive flow-weighted loads. Stratification of deployments by flow however generally resulted in noticeable improvements in passive sampler load estimates. By considering the magnitude of the uncertainty (interquartile range and the root-mean-squared error) of load estimates a modeling exercise showed that passive samplers were a viable alternative to grab sampling since between 3 and 17 grab samples were needed before grab sampling results had less uncertainty.

A passive sampling method for assessing the occurrence and risk of organophosphate flame retardants in aquatic environments

A modified polar organic chemical integrative sampler (m-POCIS) was used to determine the occurrence of and risk posed by organophosphate flame retardants (OPFRs) in the Yangtze River in Nanjing. Laboratory calibrations were performed to determine sampling rates (R_s) in different situations. R_s values increased with the flow rate, but the effect of dissolved organic matter (DOM) on R_s was relatively small. The validation of R_s in the m-POCIS for 15 days at the Yangtze River in 2015 showed that the R_s values for most of the test compounds are considerably larger than those obtained in the laboratory. The aqueous concentrations of OPFRs were estimated by using R_s values obtained in the field. OPFRs were widely distributed in the Yangtze River, with total concentrations as determined by the m-POCIS ranging from 44.95 ng/L to 118.38 ng/L. These suggest their widespread use and persistence in the river. This study also provided a protocol for the assessment of risk posed by OPFRs. It showed that tripentyl phosphate (TPeP) could pose medium risk to daphnia in the Yangtze River.

Monitoring contaminants of emerging concern from tertiary wastewater treatment plants using passive sampling modelled with performance reference compounds

The Lake Simcoe watershed in Ontario, Canada is an important recreational area and a recharge zone for groundwater resources. Lake Simcoe is a relatively shallow lotic system that has been impacted by urban development, recreation, industry and agriculture. As part of a watershed management plan, six wastewater treatment plants (WWTPs) located in this catchment basin were selected to measure the inputs of contaminants of emerging concern (CECs) of wastewater origin. These WWTPs were recently upgraded to tertiary treatment for phosphorus removal. Polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs) were used to monitor for hydrophilic and hydrophobic CECs, respectively, in treated and untreated wastewater. The passive samplers were calibrated with performance reference compounds (PRCs) by measuring the loss of deuterated beta blocker drugs spiked into POCIS and the loss of PCB congeners spiked into SPMDs over the course of 14-day deployment periods. From the PRC data, field sampling rates of CECs were determined and applied to estimate time-weighted average (TWA) concentrations and mass loadings in mg/day/1000 members of the population serviced. In treated wastewater, TWA concentrations of an antibiotic, sulfamethoxazole, the prescription drugs, carbamazepine, naproxen and gemfibrozil, and the non-prescription drug, ibuprofen, were estimated to be in the low (<18 ng/L) range. The artificial sweeteners, sucralose and acesulfame, were particularly useful chemical tracers, with estimated TWA concentrations in treated wastewater ranging from 128 to 213 ng/L and 4 to 33 ng/L, respectively. The steroid hormones were detected only rarely in treated wastewater. Triclosan, triclocarban and the synthetic musks, HHCB and AHTN, were removed efficiently (>77 %), possibly because of the tertiary treatment technologies. Therefore, the mass loadings for these personal care products were all <5 mg/day/1000 people. Overall, this study indicates that tertiary treatment technologies designed for phosphorus removal do not entirely remove the target CECs.

Aquatic passive sampling of perfluorinated chemicals with polar organic chemical integrative sampler and environmental factors affecting sampling rate

A modified polar organic chemical integrative sampler (POCIS) could provide a convenient way of monitoring perfluorinated chemicals (PFCs) in water. In the present study, the modified POCIS was calibrated to monitor PFCs. The effects of water temperature, pH, and dissolved organic matter (DOM) on the sampling rate (R s) of PFCs were evaluated with a static renewal system. During laboratory validation over a 14-day period, the uptake kinetics of PFCs was linear with the POCIS. DOM and water temperature slightly influenced POCIS uptake rates, which is in consistent with the theory for uptake into POCIS. Therefore, within a narrow span of DOM and water temperatures, it was unnecessary to adjust the R s value for POCIS. Laboratory experiments were conducted with water over pH ranges of 3, 7, and 9. The R s values declined significantly with pH increase for PFCs. Although pH affected the uptake of PFCs, the effect was less than twofold. Application of the R s value to analyze PFCs with POCIS deployed in the field provided similar concentrations obtained from grab samples.

Improvement of POCIS ability to quantify pesticides in natural water by reducing polyethylene glycol matrix effects from polyethersulfone membranes

The presence of polyethylene glycol compounds (PEG) in extracts from polar organic chemical integrative samplers (POCIS) was shown by high resolution time-of-flight mass spectrometry. PEG compounds, which are released by polyethersulfone (PES) membranes used to build POCIS, can induce matrix effects during quantification of performance reference compounds (PRC, DIA-d5) and target pesticides by mass detection, even after chromatographic separation. Dilution of POCIS extracts can reduce this matrix effect, but dilution may induce a decrease in POCIS performance, primarily for quantification limits. To reduce PEG interference during chromatographic analysis, a simple non-damaging washing protocol for PES membranes is proposed. The method consists of 2 successive baths of washing solution (140 mL per membrane) of ultrapure water (UPW) and methanol (50/50), stirred at 300 rotations per minute (rpm), followed by a final membrane rinse with UPW (140 mL). The signal from PEG compounds was significantly decreased for washed membranes (between 4 and 6 fold lower). After field deployment, total ion current chromatograms of extracts from POCIS built with washed PES membranes did not display a significant PEG fingerprint. This led to improved quantification accuracy for compounds co-eluting with PEG, i.e. PRC (performance and reference compound, DIA-d5) and some pesticides and metabolites. With washed membranes, an accurate quantification of PRC and pesticides sampled by POCIS was indeed possible without a large extract dilution; 10 times instead of the 25 times needed in unwashed conditions. Assuming that the PRC approach corrects for environmental conditions and sampling rates (Rs), a proper PRC (DIA-d5) quantification significantly improved pesticide time weighted average concentration (TWAC) determination in natural water after field deployment.

Screening breeding sites of the common toad (Bufo bufo) in England and Wales for evidence of endocrine disrupting activity

Anuran amphibians are often present in agricultural landscapes and may therefore be exposed to chemicals in surface waters used for breeding. We used passive accumulation devices (SPMD and POCIS) to sample contaminants from nine breeding sites of the Common toad (Bufo bufo) across England and Wales, measuring endocrine activity of the extracts in a recombinant yeast androgen screen (YAS) and yeast estrogen screen (YES) and an in vitro vitellogenin induction screen in primary culture of Xenopus laevis hepatocytes. We also assessed hatching, growth, survival, and development in caged larvae in situ, and sampled metamorphs for gonadal histopathology. None of the SPMD extracts exhibited estrogen receptor or androgen receptor agonist activity, while POCIS extracts from two sites in west-central England exhibited concentration-dependent androgenic activity in the YAS. Three sites exhibited significant estrogenic activity in both the YES and the Xenopus hepatocyte. Hatching rates varied widely among sites, but there was no consistent correlation between hatching rate and intensity of agricultural activity, predicted concentrations of agrochemicals, or endocrine activity measured in YES/YAS assays. While a small number of intersex individuals were observed, their incidence could not be associated with predicted pesticide exposure or endocrine activitity measured in the in vitro screens. There were no significant differences in sex ratio, as determined by gonadal histomorphology among the study sites, and no significant correlation was observed between proportion of males and predicted exposure to agrochemicals. However, a negative correlation did become apparent in later sampling periods between proportion of males and estrogenic activity of the POCIS sample, as measured in the YES. Our results suggest that larval and adult amphibians may be exposed to endocrine disrupting chemicals in breeding ponds, albeit at low concentrations, and that chemical contaminants other than plant protection products may contribute to endocrine activity of surface waters in the agricultural landscape.

Application of POCIS for exposure assessment of munitions constituents during constant and fluctuating exposure

The present study examined the potential use of polar organic chemical integrative samplers (POCIS) for exposure assessment of munitions constituents, including 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and their breakdown products (aminodinitrotoluenes [ADNTs], diaminonitrotoluenes [DANTs], and hexahydro-1,3,5-trinitroso-1,3,5-triazine [TNX]). Loss of munitions constituents from the sorbent phase after uptake was observed for the "pesticide" POCIS configuration but not for the "pharmaceutical" configuration. Therefore, the latter was selected for further investigation. Under constant exposure conditions, TNT, ADNTs, DANT, RDX, and atrazine (a common environmental contaminant) accumulated at a linear rate for at least 14 d, with sampling rates between 34 mL/d and 215 mL/d. When POCIS were exposed to fluctuating concentrations, analyte accumulation values were similar to values found during constant exposure, indicating that the sampler was indeed integrative. In contrast, caffeine (a common polar contaminant) and TNX did not accumulate at a linear rate and had a reduction in accumulation of greater than 50% on the POCIS during fluctuating exposures, demonstrating that POCIS did not sample those chemicals in an integrative manner. Moreover, in a flow-through microcosm containing the explosive formulation Composition B, TNT and RDX were readily measured using POCIS, despite relatively high turnover rates and thus reduced water concentrations. Mean water concentrations estimated from POCIS were ± 37% of mean water concentrations measured by traditional grab sample collection. Thus, POCIS were found to have high utility for quantifying exposure to most munitions constituents evaluated (TNT, ADNTs, and RDX) and atrazine.

Optimization of the polar organic chemical integrative sampler for the sampling of acidic and polar herbicides

This paper presents an optimization of the pharmaceutical Polar Organic Chemical Integrative Sampler (POCIS-200) under controlled laboratory conditions for the sampling of acidic (2,4-dichlorophenoxyacetic acid (2,4-D), acetochlor ethanesulfonic acid (ESA), acetochlor oxanilic acid, bentazon, dicamba, mesotrione, and metsulfuron) and polar (atrazine, diuron, and desisopropylatrazine) herbicides in water. Indeed, the conventional configuration of the POCIS-200 (46 cm(2) exposure window, 200 mg of Oasis® hydrophilic lipophilic balance (HLB) receiving phase) is not appropriate for the sampling of very polar and acidic compounds because they rapidly reach a thermodynamic equilibrium with the Oasis HLB receiving phase. Thus, we investigated several ways to extend the initial linear accumulation. On the one hand, increasing the mass of sorbent to 600 mg resulted in sampling rates (R s s) twice as high as those observed with 200 mg (e.g., 287 vs. 157 mL day(-1) for acetochlor ESA). Although detection limits could thereby be reduced, most acidic analytes followed a biphasic uptake, proscribing the use of the conventional first-order model and preventing us from estimating time-weighted average concentrations. On the other hand, reducing the exposure window (3.1 vs. 46 cm(2)) allowed linear accumulations of all analytes over 35 days, but R s s were dramatically reduced (e.g., 157 vs. 11 mL day(-1) for acetochlor ESA). Otherwise, the observation of biphasic releases of performance reference compounds (PRC), though mirroring acidic herbicide biphasic uptake, might complicate the implementation of the PRC approach to correct for environmental exposure conditions.

Presence and transport of the antimicrobials triclocarban and triclosan in a wastewater-dominated stream and freshwater environment

The presence of the antimicrobials triclocarban (TCC) and triclosan (TCS)in Fountain Creek, a wastewater-dominated stream, and the Arkansas River, Colorado, USA was measured in the surface water, suspended sediments, and bed sediments during spring runoff (high flow) and summer base flow (low flow) conditions. Fountain Creak is a tributary of the Arkansas River. Passive polar organic chemical integrative samplers (POCIS) were used along with active sampling (water grab samples) to measure and TCS concentrations in these surface waters. The concentration of TCC and TCS, based on POCIS measurements, ranged from 4.5 to 47.3 ng/L and 3.9 to 28.3 ng/L, respectively, at the five sample sites monitored in this study under both flow conditions. The range of concentrations of TCC and TCS in suspended sediments was 0.7-57.3 ng/g and 0.7-13.3 ng/g, respectively, and was closely tied to the quantity of organic carbon in the suspended sediment, which ranged from 1.6 to 14.5%. The quantity of organic carbon in suspended sediment during the summer base flow was influenced by runoff from the burn area of a large forest fire that occurred between the two sampling periods. The primary transport mechanism of TCC and TCS in these surface waters was in the dissolved phase, with 64-99% of TCC and 68-99% of TCS transported in the dissolved phase. The total amount of TCS and TCC in bed-sediments was relatively low, with the maximum amount at any one site being 0.38 ± 0.15 ng/g TCS and 4.09 ± 5.26 ng/g TCC. Fountain Creek contributed up to 76% and 69% of the TCC and TCS, respectively, that is transported directly below its confluence with Arkansas River. Fountain Creek drained approximately 3.0 g/day TCS (in spring), 2.9 g/day TCS (in summer) and 1.9 g/day TCC (in spring), 2.0 g/day TCC (in-summer) into the Arkansas River, which suggests consistent input of TCC and TCS into Fountain Creek, such as in discharge of treated wastewater that is independent of changing creek flow conditions.

In-situ calibration of POCIS for the sampling of polar pesticides and metabolites in surface water

Over the past years, passive sampling devices have been successfully used for the monitoring of various pollutants in water. The present work studied the uptake kinetics in surface water of ten polar pesticides and metabolites, using pharmaceutical POCIS samplers. The aim was to determine sampling rates from in-situ calibration and to compare results with those obtained earlier under laboratory conditions, with the final objective of assessing the impact of environmental conditions on POCIS field performance. Field results showed a low efficiency of POCIS uptake capacity for moderately polar compounds, such as propiconazole (log Kow=3.72) and tebuconazole (log Kow=3.7), that were present in the aqueous phase at very low levels. The in-situ sampling rates obtained in this study ranged from 169 to 479 mL g(-1)day(-1) and differ by a factor of 3-7.5 from Rs determined under laboratory conditions.

Use of mixed-mode ion exchange sorbent for the passive sampling of organic acids by polar organic chemical integrative sampler (POCIS)

Acidic herbicides are increasingly monitored in freshwater, since their high solubility favors their rapid transfer to the water phase. Therefore, contaminant levels in the water can vary rapidly and passive sampling would be preferred over spot sampling to integrate all pollution events over a given exposure time. In this work, we propose to compare the conventional pharmaceutical polar organic chemical integrative sampler (POCIS) with modified POCISs containing two different receiving phases: a standard polystyrene divinylbenzene polymer with a higher specific surface area (Chromabond HR-X) and a mixed-mode anion exchange sorbent providing additional strong anion exchange interaction sites (Oasis MAX). Due to its hydrophobic character, Chromabond HR-X had little interaction with water (no sampling of acidic herbicides); whereas Oasis MAX provided acceptable sampling parameters (longer kinetic regime together with higher sampling rates). Additional experiments with POCIS-MAX showed no influence of nitrates on analyte uptakes, and linear isotherms reaching 10 μg L⁻¹, supporting the applicability of this device for the sampling of organic acids in continental water. The performance and reference compound (PRC) approach would be then applicable for POCIS-MAX if no competition is observed with other anions, especially organic acids (e.g., humic acids).

Calibration and use of the polar organic chemical integrative sampler--a critical review

The implementation of strict environmental quality standards for polar organic priority pollutants poses a challenge for monitoring programs. The polar organic chemical integrative sampler (POCIS) may help to address the challenge of measuring low and fluctuating trace concentrations of such organic contaminants, offering significant advantages over traditional sampling. In the present review, the authors evaluate POCIS calibration methods and factors affecting sampling rates together with reported environmental applications. Over 300 compounds have been shown to accumulate in POCIS, including pesticides, pharmaceuticals, hormones, and industrial chemicals. Polar organic chemical integrative sampler extracts have been used for both chemical and biological analyses. Several different calibration methods have been described, which makes it difficult to directly compare sampling rates. In addition, despite the fact that some attempts to correlate sampling rates with the properties of target compounds such as log K(OW) have been met with varying success, an overall model that can predict uptake is lacking. Furthermore, temperature, water flow rates, salinity, pH, and fouling have all been shown to affect uptake; however, there is currently no robust method available for adjusting for these differences. Overall, POCIS has been applied to a wide range of sampling environments and scenarios and has been proven to be a useful screening tool. However, based on the existing literature, a more mechanistic approach is required to increase understanding and thus improve the quantitative nature of the measurements.